Hi guys (and gals), new poster here in need of some help please. I have a 2001 2500HD/8.1L and it's acting very strangely. It started about a month ago when I had just filled up and was stopped at a light and the low fuel light came on. The fuel gauge showed completely empty. As soon as I gave it some gas to go, the gauge snapped up to full and off we go. It has progressively gotten worse, doing that whenever I am in idle. Sometimes the gauge snaps back to actual reading and other times it veerrryyy slowly comes up. I was thinking it was either the pump or the fuel level sensor then a few days ago my wife calls me in panic. The truck just shut off while stopped at a light. It happens very rarely but it died on me on the freeway at 73...I mean 65. I pumped the pedal a few times and the engine snaps back to life. It seems to happen when you are pulling your foot off the gas. I checked the codes and it is spitting P0101 which after a few days of digging around seems to indicate Mass Air Flow (MAF) Circuit Range/Performance Problem which could mean anything from the MAF to the MAP to PCV or EGR or... I have read just about everything from air intake through exhaust. The truck has around 75K miles (yes, we baby it) but that was about the time that my old '96 1500's pump went out.
Before I go drop the tank and cough up $250-300 on a new pump, I was wondering if anyone else smarter than me had any ideas as to what the heck is going on. I'd hate to drop the money just to find out it was a $60 MAP sensor.
I appreciate the time.

 

I have a 2001 Sierra 2500HD crew cab with the 8.1L and have experienced all the same issues you described. I am not an expert but in my experience all three symptoms you described are separate problems. As far as the engine cutting out, in both cases I have dealt with it was a Crank Shaft sensor. My dad has a 2001 Silverado 3500 with the 8.1L his was the first to mess up, engine would shut off without warning at any time, idle/on the gas/off the gas/while driving, it didn’t seem to matter. This was a few years ago and I don’t remember what all he replaced before he put a new crank sensor in and the problem went away. I bought my truck a little over three years ago and just last year had the same problem, driving down the highway “65mph of course” and the engine dies, jumped off at the next exit and stopped. After a few attempted starts and cycles of the key starts right back up like nothing happened. That weekend I put a new crank sensor in (think it was $50 at Advance auto Parts) and it has never happened again. I have also read on some other sites and forums of this same problem, and crank sensor being the solution. Now with the fuel gauge and light going crazy it has been like that since I bought it (bought it at 72,xxx miles) with mine it happens when the truck is sitting still, fuel gauge drops and the light comes on, as soon as I start moving again light goes off and the gauge jumps back up where it was. When I fill up with gas the gauge takes forever to move back up. I have not tried to fix this yet but from what I have been told (if I am wrong on this someone please correct me) 2001 is the first year GM used plastic fuel tanks and there are no baffles in the tank to stop the gas from sloshing around and after a few years and several thousand miles of the gas sloshing around it wears out the fuel sender. Mine has been this way for a few years and it has never affected the engine or caused it to die. I believe the fuel pump is fine the fuel sender/fuel level sensor has worn out over time. Now with the code you are getting (I was getting the same one, but there are so many reasons for this we may not have the same issue here) , mine started showing up right after I put a K&N air filter in. I believe I had too much oil in the filter and it ‘gummed” up my mass air flow sensor. I put the original filter back in and still got the check engine light and code. Just cleaned the Sensor and have not got the light or code yet but it’s only been a week or so. With my truck all three of these happened at different times and where not related at all. I would recommend putting in a new Crank Shaft Sensor ($50, took maybe an hour and some scraped knuckles from the small space they jam it in) but I think that will fix the problem with the engine cutting out. In my case the other two are separate issues as well, I have not fixed the fuel sender problem yet (I have all ways had something higher up on the list of things to do) and hopefully my mass air flow is fixed already. But good luck to you hope it’s as easy to fix as mine was.